The journal “Konstruktion”, Zeitschrift für Produktentwicklung und Ingenieur-Werkstoffe [journal for product development and engineering materials], Volume 55, No. 9, page IW 9, discloses a heat exchanger tube which has ribs running along its longitudinal axis, lying on the inside and twisted about the main flow direction. The ribs serve to enlarge the inner surface of the tube and to produce a swirl in the medium flowing through the tube. This is intended to achieve an increase in the heat transfer compared with a smooth tube.
Furthermore, for example, a turbine blade as a cooled component of a gas turbine is known. The hot working medium produced in a gas turbine by the combustion of a fuel flows along the blades of a rotor in order to produce rotary energy. In order to protect the blades against the hot temperatures, said blades are cooled by means of air or steam. To this end, the blades of the gas turbine have a passage which runs in the interior of the airfoil in the region of a leading edge and extends in the radial direction of the rotor. A cooling fluid flowing in this passage cools the leading edge, which is especially subjected to thermal stress. Such a blade has been disclosed, for example, by DE 197 38 065 A1.